1. Field of the Invention
The present disclosure relates to auxiliary power units, and more particularly to inlet doors of auxiliary power units.
2. Description of Related Art
Auxiliary power units (“APU”) are used in aircraft to provide electrical power and compressed air to various onboard systems. When an aircraft is on the ground, often its main source of electrical power and pneumatic power comes from the APU, e.g., when the main engines are not engaged. Generally, APUs are located in the aft section of the aircraft, at or near the tailcone section, and utilize an air intake system to allow sufficient air flow to travel from an opening in the exterior surface of the airplane through to the APU. Air intake systems typically include an inlet air door to protect the APU from foreign object damage when not in use and/or during ground movement, and to maximize airflow into the APU when performance at altitude is required. Thus, when APU venting is desired, the inlet air door opens, whether on the ground or in flight.